MCD19A2 v061

MODIS/Terra+Aqua Land Aerosol Optical Depth Daily L2G Global 1 km SIN Grid

PI: Alexei Lyapustin


The MCD19A2 Version 6.1 data product is a Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua combined Land Aerosol Optical Depth (AOD) gridded Level 2 product produced daily at 1 kilometer (km) pixel resolution. The MCD19A2 product provides the atmospheric properties and view geometry used to calculate the Multi-angle Implementation of Atmospheric Correction (MAIAC) Land Surface Bidirectional Reflectance Factor (BRF) or surface reflectance, MCD19A1 product.

The MCD19A2 AOD data product contains the following Science Dataset (SDS) layers: blue band AOD at 0.47 µm, green band AOD at 0.55 µm, AOD uncertainty, fine mode fraction over water, column water vapor over land and clouds, smoke injection height, AOD QA, Angstrom Exponent over the ocean, cosine of solar zenith angle, cosine of view zenith angle, relative azimuth angle, scattering angle, and glint angle. A low-resolution browse image is also included showing AOD of the blue band at 0.47 µm, created using a composite of all available orbits.

Each SDS layer within each MCD19A2 Hierarchical Data Format 4 (HDF4) file contains a third dimension that represents the number of orbit overpasses. This factor could affect the total number of bands for each SDS layer.

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Improvements/Changes from Previous Versions

  • The Version 6.1 Level-1B (L1B) products have been improved by undergoing various calibration changes that include: changes to the response-versus-scan angle (RVS) approach that affects reflectance bands for Aqua and Terra MODIS, corrections to adjust for the optical crosstalk in Terra MODIS infrared (IR) bands, and corrections to the Terra MODIS forward look-up table (LUT) update for the period 2012 - 2017.
  • A polarization correction has been applied to the L1B Reflective Solar Bands (RSB).
  • The MCD19 Version 6.1 products have added 250 meter (m) resolution bands.
  • The previous BRDF product (MCD19A3) was reported once every eight days and the new MCD19A3D is a daily product.
  • MCD19A3D introduces gap-filled NDVI and gap-filled 250 m NBAR.
  • Snow Fraction, Snow Fit, and Snow Grain Size layers were moved from MCD19A1 to the MCD19A3D.
  • There are four additional Climate Modeling Grid (CMG) products: MCD19A1CMGL, MCD19A1GO, MCD19A2CMG, and MCD19A3CMG.

Product Maturity

Validation at stage1 has been achieved for the MODIS AOD product. Further details regarding MODIS land product validation for MCD19 data products are available from the MODIS Land Team Validation site.

Collection and Granule


Characteristic Description
CollectionCombined MODIS
File Size~4 MB
Temporal ResolutionDaily
Temporal Extent2000-02-24 to Present
Spatial ExtentGlobal
Coordinate SystemSinusoidal
File FormatHDF-EOS
Geographic Dimensions1200 km x 1200 km


Characteristic Description
Number of Science Dataset (SDS) Layers13
Columns/Rows1200 x 1200
Pixel Size1000 m

Layers / Variables

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
Optical_Depth_047 Blue band (0.47 μm) aerosol optical depth over land N/A 16-bit signed integer -28672 N/A -100 to 6000 0.001
Optical_Depth_055 Green band (0.55 μm) aerosol optical depth over land N/A 16-bit signed integer -28672 N/A -100 to 6000 0.001
AOD_Uncertainty AOD uncertainty based on blue-band surface brightness (reflectance) N/A 16-bit signed integer -28672 N/A -100 to 30000 0.0001
FineModeFraction Fine mode fraction for ocean N/A 32-bit floating point -99999 N/A 0 to 1000 N/A
Column_WV Column Water Vapor (cm) over land cm 16-bit signed integer -28672 N/A 0 to 8000 0.001
Injection_Height Smoke injection height (m above ground) Meters 32-bit floating point -99999 N/A 0 to 10000 N/A
AOD_QA AOD QA N/A 16-bit unsigned integer 0 N/A 1 to 65535 N/A
AngstromExp_470- 780 Angstrom Exponent 470-780nm over the ocean N/A 16-bit signed integer -28672 N/A -5000 to 30000 0.0001
cosSZA Cosine of Solar zenith angle (5 km) N/A 16-bit signed integer -28672 N/A 0 to 10000 0.0001
cosVZA Cosine View zenith angle (5 km) N/A 16-bit signed integer -28672 N/A 0 to 10000 0.0001
RelAZ Relative azimuth angle (5 km) N/A 16-bit signed integer -28672 N/A -18000 to 18000 0.01
Scattering_Angle Scattering Angle (5 km) N/A 16-bit signed integer -28672 N/A -18000 to 18000 0.01
Glint_Angle Glint Angle (5 km) N/A 16-bit signed integer -28672 N/A -18000 to 18000 0.01

The MCD19 SDS layers are three dimensional. The total number of bands in each file is contingent upon the number of orbit overpasses (1-2 bands at the equator and up to 30 bands in polar regions). For example, a file with an orbit number of five will contain five bands for each SDS layer (e.g., FineModeFraction will be recorded in 5 separate instances). Note that at high latitudes, only the first 16 orbits with the largest coverage are selected for processing per day in order to limit the file size.

Orbit information is stored in the Orbit_amount and Orbit_time_stamp attributes in the HDF file. The global metadata attributes of MODIS data products can be viewed in software such as HDFView and Panoply.

Product Quality

Quality assurance information should be considered when determining the usability of data for a particular science application. The ArcGIS MODIS-VIIRS Python Toolbox contains tools capable of decoding quality data layers while producing thematic quality raster files for each quality attribute.

The QC layer is stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret the QC layers.

Product quality information is described in Section 6 of the User Guide.

Known Issues

Known issues are described in Section 6 of the User Guide. For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website.

About the image

Combined MODIS Optical Depth 047 data from the MCD19A2 product over part of west Africa, January 9, 2001.

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User Guide
Algorithm Theoretical Basis Document (ATBD)
File Specification

Using the Data

Access Data


DOI: 10.5067/MODIS/MCD19A2.061